With respect to number 5: Yogi Berra once is said to have said, "In theory there is no difference between theory and practice. In practice there is." Theory states that the "hull speed" - maximum speed of a displacement boat - can be closely approximated in knots by 1.39 times the square root of the water line in feet. The displacement hull sits in the trough between the trailing edge of the bow wave and the leading edge of the stern wave created as the hull moves through the water. The bow and stern wave fronts move together at a speed proportional to their separation distance. So in theory there is a limit to how fast a displacement hull moves -- namely the maximum speed of these two wave fronts. In practice however, once a sail boat reaches hull speed additional energy usually produces excessive heal, wind is dumped out of the sails, and the boat stays in the trough. In practice, even a displacement hull can be forced to ride up onto the trailing edge of the bow wave forcing the boat to go faster than the theoretical hull speed without getting up on a plane.